Human dimensions research has produced a large number of advances in knowledge about global change, as the previous section indicated in some detail. In general, recent research has refined earlier understanding of human-environment interactions in ways that will enable more accurate modeling and anticipation of global change and its impacts and better-informed policy responses. Many of the major advances in knowledge can be summarized in a few major categories.
Relative Importance of Socioeconomic Uncertainty
Several analyses clearly indicate that socioeconomic uncertainties dominate biophysical uncertainties in assessing future climate impacts. Because of the great significance to the future of environmental change of such phenomena as rates of economic growth and adoption of environmental technology, which can only be forecast with great uncertainty, relatively small improvements in our understanding of these phenomena can significantly improve the ability to anticipate and respond to the effects of climate change. The same reasoning may apply to ecological changes, the rates of which are also sensitive to socioeconomic factors, such as human demands for land and water, the long-term forecasts of which are highly uncertain.
Complex Determination of Environmentally Significant Consumption
The term "consumption" has different meanings in different scientific disciplines; research on environmentally significant consumption focuses on human activities, such as clearing forests and using fossil energy, that transform or degrade biophysical resources and thus affect things that people value. Accumulating evidence indicates that all of the environmentally significant kinds of consumption are determined by multiple factors, including such driving forces as population growth, economic and technological development, cultural forces, values and beliefs, political activity, institutions, and policies and by the interactions of these forces. Research shows that the interactions are typically specific to the type of consumption, the responsible decision maker, and the geographic and sociopolitical context. Studies are illuminating the operations of the driving forces as they affect particular types of consumption (energy, forest clearing) in particular contexts.
Human dimensions research is also advancing our understanding of some of the driving forces. It has documented the widespread global support for environmental protection and some of the reasons for that support, the many factors influencing environmentally significant consumption by individuals and households, the trend toward globalization of trade in environmentally significant goods
and services, the increasing importance of human population migrations as an environmental threat, and the environmental significance of major technological trends affecting the rates of substitution of inexhaustible resources for depletable ones.
Importance of Vulnerability Analysis in Impact Assessment
Research on the impacts of past climatic variability on societies and economies shows that these impacts depend as much on the social systems that produce vulnerability as on the biophysical systems that cause environmental change. Vulnerability depends on a number of factors, including intensity of land and water use and population immigration in marginal areas, access to economic resources, infrastructure for hazard response, the health status of potentially affected populations, and the structure of the hazard management systems a society has in place to prepare for and manage environmental events. Vulnerability analyses are essential for estimating the human impacts of environmental change and variation. For instance, climate models can be linked to crop models and estimates of vulnerability to provide early warnings of famine, and ecological models can be linked to vulnerability analyses to estimate the effects of global change and climate variability on human health.
Importance of Institutional Design to Environmental Resource Management
Research on human use of common-pool resources has shown that the "tragedy of the commons" scenario is not inevitable. Tragedy has often been prevented and resources sustained over periods of generations to centuries by the design of institutions that monitor the conditions of resources locally, effectively govern access to them, establish norms of resource use and sanctions for overexploitation, and appropriately link local institutions with those at higher levels. A key to implementing effective responses to global change is to design incentive-compatible institutions, that is, institutions capable of internalizing the overall costs of environmental degradation for the individuals, private firms, and public organizations whose actions create environmental stress. Ongoing research on existing institutions and on the theory of institutional design is clarifying the conditions for successful long-term environmental resource management and the institutional structures that have been successful with particular types of resources. Better understanding of institutions that shape human interactions with the environment, these institutions' functioning, and their linkages is essential to forecasting global change and developing policy responses that reduce vulnerability as well as to effective long-term resource management.
Importance of Both Analysis and Deliberative Procedure in Environmental Decision Making
Wise environmental policy making requires good analyses of the various kinds of values and costs associated with environmental change and of the values and costs associated with available policy options. Human dimensions researchers are developing and refining analytical procedures for environmental accounting and valuation, cost-benefit analysis, and other tools to estimate the costs of global change and of policy response options. However, research also shows the dependence of these analyses on highly contestable judgments in areas where knowledge is incomplete and where value disagreements are significant, such as in estimating nonmarket values and intergenerational equity. One lesson is that, in addition to reliable analytical procedures, wise decision making depends on developing appropriate and acceptable processes for deliberating about analytical assumptions and identifying information needs among scientists, policy makers, and others interested in global change decisions. Research on the effectiveness of various deliberative procedures is in its infancy compared with research on analytical techniques.
Importance of a Broad-Based Infrastructure
A broad national and international infrastructure is developing for research and policy development on the human dimensions of global environmental change. Within the USGCRP the effort has broadened from a program of investigator-initiated studies funded by NSF to encompass some larger and more focused NSF initiatives, such as a set of human dimensions centers and teams and efforts on policy research and global change and on methods and models for integrated assessment; significant research activities by the U.S. Department of Energy (DOE) and its laboratories, the U.S. Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), and the National Institutes of Health; smaller research programs at NASA, the U.S. Department of Agriculture, the U.S. Department of the Interior (DOI), and the National Institute of Child Health and Human Development; and highly promising interagency collaborations between NSF and EPA on watersheds and on valuation and decision making. It has proven especially important to find ways to meld a strong social scientific base with substantive focus on global change questions. Useful strategies have included interdisciplinary review of proposals; development of problem-focused initiatives at NSF; incorporation of strong social science input into the peer review process in mission agencies, sometimes drawing on NSF for support; and formal interagency collaborations.
It is also important to encourage international collaborations, to exchange ideas, improve access to data, engage in international comparative research, and take advantage of synergism among research efforts. The IHDP, under the aus-
pices of the International Council of Scientific Unions and the International Social Science Council, has brought the international research community together in two major international conferences148 and now has active core projects on land use and land cover change, industrial transformation, environmental security, and institutions. The IHDP currently provides a framework for collaboration among social scientists and coordination of national human dimensions programs. The IPCC also provides an important forum for the interchange of ideas concerning the human causes, impacts, and responses to climate change. Recently, regional networks and organizations, such as the Asia Pacific Network, the Inter American Institute, the European Community, and the System for Analysis, Research, and Training (START) are developing human dimensions research programs.
Significance of Improved Observational Methods and Data Systems
Observation, that is, the collection of data, relies on sources ranging from remote sensing platforms on satellites to social surveys. The quality of social data that serve global change research has been improved by applying cognitive laboratory techniques to the way survey questions are asked and using multilevel models and datasets to incorporate community, household, and individual factors into the same analyses. Longitudinal datasets collected by the U.S. government, such as the Residential Energy Consumption Survey, the Nationwide Personal Transportation Survey, the Consumer Expenditure Survey, the National Longitudinal Survey of Youth, the National Survey of Families and Households, and others, have permitted the use of more complex statistical models to understand underlying causal processes. These techniques have been further developed through privately conducted government-funded surveys, such as the Panel Study of Income Dynamics and the General Social Survey. New multicountry survey studies of environmental beliefs, attitudes, and consumer behavior will benefit from these advances.
Systems for linking datasets and increasing their availability provide opportunities for major advances in human dimensions research. The past 10 years have seen the establishment or linkage of several international databases of use in studying the human dimensions of global change. For example, a 1996 report149 on the global environment provides an accessible compilation of international environmental trends at the country level from disparate sources, including various United Nations agencies and the World Bank. It is becoming the norm in the human dimensions community that data collected with federal funds should be placed in the public domain. The key issue now is implementation. The NASA-supported Social and Economic Data and Applications Center (SEDAC) is charged with making social, economic, and Earth science data available to the entire research and policy community. SEDAC also hosts a World Data Center—A, covering human interactions with the environment, and a data system for